/*
 * Copyright (C) 2009 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.mariotaku.gallery3d.ui;

import javax.microedition.khronos.egl.EGL10;
import javax.microedition.khronos.egl.EGLConfig;
import javax.microedition.khronos.egl.EGLDisplay;

import org.mariotaku.gallery3d.common.ApiHelper;

import android.opengl.GLSurfaceView.EGLConfigChooser;
import android.util.Log;

/*
 * The code is copied/adapted from
 * <code>android.opengl.GLSurfaceView.BaseConfigChooser</code>. Here we try to
 * choose a configuration that support RGBA_8888 format and if possible,
 * with stencil buffer, but is not required.
 */
class GalleryEGLConfigChooser implements EGLConfigChooser {

	private static final String TAG = "GalleryEGLConfigChooser";

	private final int mConfigSpec565[] = new int[] { EGL10.EGL_RED_SIZE, 5, EGL10.EGL_GREEN_SIZE, 6,
			EGL10.EGL_BLUE_SIZE, 5, EGL10.EGL_ALPHA_SIZE, 0, EGL10.EGL_NONE };

	private final int mConfigSpec888[] = new int[] { EGL10.EGL_RED_SIZE, 8, EGL10.EGL_GREEN_SIZE, 8,
			EGL10.EGL_BLUE_SIZE, 8, EGL10.EGL_ALPHA_SIZE, 0, EGL10.EGL_NONE };

	private static final int[] ATTR_ID = { EGL10.EGL_RED_SIZE, EGL10.EGL_GREEN_SIZE, EGL10.EGL_BLUE_SIZE,
			EGL10.EGL_ALPHA_SIZE, EGL10.EGL_DEPTH_SIZE, EGL10.EGL_STENCIL_SIZE, EGL10.EGL_CONFIG_ID,
			EGL10.EGL_CONFIG_CAVEAT };

	private static final String[] ATTR_NAME = { "R", "G", "B", "A", "D", "S", "ID", "CAVEAT" };

	@Override
	public EGLConfig chooseConfig(final EGL10 egl, final EGLDisplay display) {
		final int[] numConfig = new int[1];
		final int mConfigSpec[] = ApiHelper.USE_888_PIXEL_FORMAT ? mConfigSpec888 : mConfigSpec565;
		if (!egl.eglChooseConfig(display, mConfigSpec, null, 0, numConfig))
			throw new RuntimeException("eglChooseConfig failed");

		if (numConfig[0] <= 0) throw new RuntimeException("No configs match configSpec");

		final EGLConfig[] configs = new EGLConfig[numConfig[0]];
		if (!egl.eglChooseConfig(display, mConfigSpec, configs, configs.length, numConfig))
			throw new RuntimeException();

		return chooseConfig(egl, display, configs);
	}

	private EGLConfig chooseConfig(final EGL10 egl, final EGLDisplay display, final EGLConfig configs[]) {

		EGLConfig result = null;
		int minStencil = Integer.MAX_VALUE;
		final int value[] = new int[1];

		// Because we need only one bit of stencil, try to choose a config that
		// has stencil support but with smallest number of stencil bits. If
		// none is found, choose any one.
		for (int i = 0, n = configs.length; i < n; ++i) {
			if (!ApiHelper.USE_888_PIXEL_FORMAT) {
				if (egl.eglGetConfigAttrib(display, configs[i], EGL10.EGL_RED_SIZE, value)) {
					// Filter out ARGB 8888 configs.
					if (value[0] == 8) {
						continue;
					}
				}
			}
			if (egl.eglGetConfigAttrib(display, configs[i], EGL10.EGL_STENCIL_SIZE, value)) {
				if (value[0] == 0) {
					continue;
				}
				if (value[0] < minStencil) {
					minStencil = value[0];
					result = configs[i];
				}
			} else
				throw new RuntimeException("eglGetConfigAttrib error: " + egl.eglGetError());
		}
		if (result == null) {
			result = configs[0];
		}
		egl.eglGetConfigAttrib(display, result, EGL10.EGL_STENCIL_SIZE, value);
		logConfig(egl, display, result);
		return result;
	}

	private void logConfig(final EGL10 egl, final EGLDisplay display, final EGLConfig config) {
		final int value[] = new int[1];
		final StringBuilder sb = new StringBuilder();
		for (int j = 0; j < ATTR_ID.length; j++) {
			egl.eglGetConfigAttrib(display, config, ATTR_ID[j], value);
			sb.append(ATTR_NAME[j] + value[0] + " ");
		}
		Log.i(TAG, "Config chosen: " + sb.toString());
	}
}
